N'nitrosonornicotine (NNN) is an important cyclic nitrosamine which may be involved in the increased incidence of cancer of the oral cavity, esophagus, pancreas, and bladder in smokers and chewers of tobacco. NNN occurs at high levels in tobacco (0.1-90 ppm) and tobacco smoke (140-250 ppb) and is carcinogenic in the rat, hamster, and mouse. It is the purpose of this proposal to determine the critical pathways of metabolic activation vs. detoxification of NNN, to develop a metabolic profile for this compound, and to determine the effect of environmental modifiers on its metabolism and carcinogenicity. In order to develop a metabolic profile, the initial intermediates resulting from alpha-hydroxylation (aldehydic diazotic acids) will be synthesized and their products examined and compared to those arising when 14C-NNN is administered to rats. Nitrosamine containing metabolites will also be profiled with the aid of the nitrosamine specific Thermal Energy Analyzer. When the profiles are developed, the effects of benzo(a)pyrene, nicotine, cotinine, catechol, alcohol, arecoline, betel nut extract, and Beta-naphthylamine on NNN metabolism will be determined and the modifiers having the greatest effects will be bioassayed with NNN. Major nitrosamine containing metabolites will also be examined for carcinogenic activity. It is expected that this study will clarify the metabolic activation of cyclic nitrosamines and the modes of development of tobacco-related cancers in man.